Understanding and Evaluating the Durability of Weighing Instruments

Shared description of "durability" from various standards is summarized. The difference between "durability" and "stability" is analyzed. The essence of wear-out and life regarding durability of non-disposable weighing instruments is pointed out. The test objects, test items, test occasions and test sites for evaluating the durability of weighing instruments are analyzed. Based on the understanding of the durability of weighing instruments, discussions are made on the durability test clauses in existing international recommendations or national standards. Difference between the in-service inspections carried out by legal metrology institutes and by users are examined. The following items are compared for durability tests made on type evaluation, on initial verification and subsequent verification, and on in-service inspection carried out by legal metrology institutes or users: test occasions, test objects, test functions, test purposes, test proposers and executors, test sites and working conditions, the criteria of durability, and the documents in which the test results should be included.